Hey Adan, these were sold as only having one size. Because the hipbelt is only webbing, and therefore meant for stabilization, rather than actual weight transfer, the size isn't as important. I am an 18.5 torso, and with the frame in, it felt good. The plastic frame has a preset curve in it. Might be better for someone, with a slightly smaller torso than my own. However, I found that the pack is better if you add your own foam frame, either rolled up like a burrito, or if you just insert a small sitpad section in the frame pocket. Makes it lighter, and makes sizing unimportant. hope that helps!